A mobile unit may (MU) be configured with a transceiver to communicate with a network. The transceiver is coupled to an antenna such that the transceiver is capable of connecting to the network on a particular operating frequency of the network. Accordingly, the antenna is designed to transmit/receive signals from the transceiver to the network on the operating frequency. For example, a cellular network in Europe is based upon a Global System for Mobiles (GSM) network utilizing a high-band frequency of 1900 MHz. In another example, a cellular network in the United States is based upon a Code Division Multiple Access (CDMA) network utilizing a high-band frequency of 1800 MHz. In yet another example, a low-band frequency ranging between 800-900 MHz may also be used such as in cellular networks. Therefore, the antenna allows the transceiver to operate on these frequencies.
A conventional MU may include a respective antenna for each operating frequency, thereby enabling the transceiver to transmit/receive signals in different networks. That is, the MU may include a first antenna to operate in the GSM network, a second antenna to operate in the CDMA network, and a third antenna to operate in the cellular network. However, this requires multiple antennas to be disposed within the housing of the MU, each antenna requiring respective connections/components.
In addition, the antenna may experience a variety of different factors that may detune the frequency at which the antenna is to operate. That is, the MU is generally not used such that there is no interference during use. FIG. 1A shows a first conventional manner of use for a MU and FIG. 1B shows a second conventional manner of use for the MU. Specifically, in a first use 10, the MU is raised to a user's head. In a second use 20, the MU is held in a user's hand. With either the first use 10 or the second use 20, the user creates an interference. Specifically, a detuning effect is present. FIG. 1C shows an effect on frequency from the conventional manners of use of the MU. A finger effect detuning graph 30 illustrates how the interference from the user affects the frequency with which the antenna operates.
FIG. 2A shows a conventional system 40 of a combined antenna 50 having a tuning element 60 as is known in the art. If a conventional combined antenna 50 includes multiple portions, the tuning element 60 is coupled to an end of the conventional combined antenna 50. As illustrating a coupling 70 may be utilized at the end such that the tuning element 60 is coupled. However, by coupling the tuning element 60 at the end of the conventional combined antenna 50, several drawbacks are presented.
FIG. 2B is a graph illustrating the frequencies of the conventional combined antenna 50 of FIG. 2A. As shown, operation of the conventional combined antenna 50 in the high-frequency band has significant shifts. Specifically, the energy usage (e.g., voltage) that runs through the conventional combined antenna 50 having the tuning element 60 at the end causes the high-frequency band operation to have adverse effects. The dark, solid line of the graph of FIG. 2B represents an operation in the high-frequency band when no interference is experienced. However, the use of the tuning element 60 disposed at the end of the combined conventional antenna 50 causes the operation lines to shift dramatically. That is, the high-frequency band operation from the use of the tuning element 60 creates significant disturbance therein. This is due to the long arm of the conventional combined antenna 50 in addition to the main operation frequency of the low band in which third harmonics operate at the high band. Coupling to this long arm at the end thereby affects both the low band and the high band.
Accordingly, there is a need for a combined antenna that is capable of operating in at least two high-band frequencies and a low frequency so that the combined antenna is capable of being used in global applications while also capable tuning the antenna to compensate for any detuning effect or guaranteeing that the antenna operates at a predetermined frequency.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.